The present invention relates to mechanical drive couplings and, more particularly, to a temporary repair device for mechanical drive couplings.
Mechanical drive couplings are often used to provide a driving connection between power supplies such as a motor and mechanisms to be driven, such as a pump, a gear reduction unit or the like. Based on the difficulty of exactly aligning the components of such systems, flexible drive couplings are used to accommodate reasonable degrees of non-alignment between the shaft members of the power source and the driven component.
One type of flexible drive coupling includes a rigid half and a flexible half. The flexible half is fixed to either the driving or driven shaft and rotates about the centerline of the shaft to which it is connected. The flexible half is a two-part assembly including a coupling shell and a coupling hub. The coupling shell is fixed to the rigid half. The coupling hub includes external gear elements which mesh with internal gear elements of the coupling shell. The coupling hub may move within the coupling shell to accommodate for misalignment between the driving and driven shafts while maintaining a rotary power interconnection between the rigid half and the flexible half.
While these gear type flexible drive couplings have performed sufficiently in the past, concerns arise. Specifically, the gear interface between the coupling hub and the coupling shell sometimes fails. The failure is usually due to friction created from excessive misalignment, lack of lubrication or both. When the coupling fails, the gear segments of the hub slide past the gear segments of the shell. As such, torque is not transmitted through the flexible drive coupling. Once the coupling no longer transmits torque, the alternatives available include replacing the coupling or making a temporary repair to the existing coupling. Unfortunately, a new coupling is often not available due to the variety of coupling types and sizes used. Furthermore, the cost of maintaining a complete selection of service stock is prohibitive. Therefore, it would be advantageous to repair the existing coupling in order to be able to minimize down time and use the machinery while waiting for a replacement coupling to arrive.
Several repair methods have been attempted. One method includes welding the shell to the hub. This repair eliminates any flexibility in the joint and usually fails within a very short period of time. Another repair method includes burning a hole through the shell and welding a post to both the hub and the shell. This repair typically does not perform well and suffers repeated breakdowns.
Accordingly, it is an object of the present invention to provide a temporary repair device for a flexible drive coupling which is durable and capable of maintaining relative movement between the coupling hub and the coupling shell.
It is a further object of the present invention to provide a temporary repair device for a flexible drive coupling that may be installed on a failed drive coupling without disassembling the components which are drivingly interconnected.
It is another object of the present invention to provide a repair device for a flexible drive coupling which is economical to stock or manufacture and easy to install.
Therefore, the present invention includes a temporary repair device for a flexible drive coupling having a shell and a hub. The repair device includes a first member fixed to the shell and a second member fixed to the hub. The first member includes a slot. A portion of the second member extends from the hub and is slidably positioned within the slot. The first and second members are drivingly engageable with one another to transfer torque between the shell and the hub while allowing the hub and shell to move relative to one another while rotating about axes which are not coaxially aligned.